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Little lost on misfires and O2 sensors...

6K views 19 replies 4 participants last post by  inthewoods 
#1 ·
Our 08 Spectra5 has very frequent misfires. Usually at the top of first gear, or early into 2nd gear. Sometimes just cruising. I would say it's very slowly getting worse. At one time I read a code 0304 but it isn't setting now. Torque Pro does report some things in test results but I'm not confident as to their meaning. 3 out of 4 tests will report these errors then another pass will be clear. Repeat.

02 bank 1 sensor 1, Min 10384 Max 41470 Current 65520
02 bank 1 sensor 1, Min 0 Max 0 Current 65520
Looks like a short or open? Then way down the list...
02 bank 1 sensor 4, Min 64.64A Max 205.78A Current 655.2A

Sensor 4? I thought there were just two?

Anyway, I haven't checked the sensors beyond making sure the harnesses were plugged in. Plugs and wires are recent and had no effect on the misfires. Gapped plugs at 032.

Any assistance would be appreciated.
 
#2 ·
@inthewoods

Just to be clear, no fault codes currently....

Not 100% sure what the figures are that you have listed above....

I have attached typical figures for O2 & fuel trim data...

You could have a vacuum leak or O2 sensor would be a good start to diagnose, once you clarify the data you have and get some other input we should be able to get you back up and running...
 

Attachments

#3 ·
Correct, no fault codes have been set since I cleared them last month. This surprised me since I expected all the misfires I've been hearing/feeling would have set the code again. Perhaps what I'm hearing isn't related to the original 0304 code?

What we hear is like a single cylinder "cough" accompanied by the very brief reduction in power. The sound is fairly loud from outside the car or with a window open. It's almost always either high in 1st gear or low in 2nd gear, though recently I've noticed it happening in both 1st and 2nd during a single acceleration. Otherwise power is very good.

The readings I posted before are just the FAILS from Torque's Test Results screen. The full list looks like:

Vehicle Calibration ID: L8NCSH1A----

Test report:
------------------
MID:$01 TID:$1a
- O2 Bank 1 Sensor 1
Max: 41,470 Min: 10,384
Test result value: 65,520
FAIL
----
MID:$01 TID:$65
- O2 Bank 1 Sensor 1
Max: 0 Min: 0
Test result value: 65,520
FAIL
----
MID:$01 TID:$91
- O2 Bank 1 Sensor 1
Max: 4.69944V Min: 0V
Test result value: 4.1968V
PASS
----
MID:$01 TID:$92
- O2 Bank 1 Sensor 1
Max: 1.99882 Min: 0
Test result value: 1.10483
PASS
----
MID:$01 TID:$93
- O2 Bank 1 Sensor 1
Max: 1.99882 Min: 0.59926
Test result value: 0.9965
PASS
----
MID:$01 TID:$94
- O2 Bank 1 Sensor 1
Max: 0.79934 Min: 0
Test result value: 0.04782
PASS
----
MID:$01 TID:$95
- O2 Bank 1 Sensor 1
Max: 50Count Min: 0Count
Test result value: 0Count
PASS
----
MID:$02 TID:$85
- O2 Bank 1 Sensor 2
Max: 0.99999Ratio Min: 0Ratio
Test result value: 0.05469Ratio
PASS
----
MID:$02 TID:$86
- O2 Bank 1 Sensor 2
Max: 7.99527V Min: 0.55144V
Test result value: 0.57584V
PASS
----
MID:$02 TID:$89
- O2 Bank 1 Sensor 2
Max: 7.99527V Min: 0.69784V
Test result value: 0.99552V
PASS
----
MID:$04 TID:$cc
- O2 Bank 1 Sensor 4
Max: 205.78A Min: 64.64A
Test result value: 655.20001A
FAIL
----
MID:$21 TID:$b4
- Catalyst Monitor Bank 1
Max: 0.5 Min: 0
Test result value: 0
PASS
----
MID:$39 TID:$a2
-
Max: -1,500Pa Min: -4,096Pa
Test result value: -1,503.25Pa
PASS
----
MID:$3a TID:$a2
- EVAP Monitor (cap off)
Max: -1,500Pa Min: -4,096Pa
Test result value: -1,503.25Pa
PASS
----
MID:$3b TID:$a2
- EVAP Monitor (0.090")
Max: 0.8 Min: 0
Test result value: 0
PASS
----
MID:$3c TID:$a2
- EVAP Monitor (0.040")
Max: 0.42 Min: 0
Test result value: 0
PASS
----
MID:$3d TID:$a8
- EVAP Monitor (0.020")
Max: 4,096Pa Min: -200Pa
Test result value: 65Pa
PASS
----
MID:$41 TID:$b0
- O2 Heater Monitor Bank 1 - Sensor 1
Max: 30Count Min: 0Count
Test result value: 0Count
PASS
----
MID:$42 TID:$b0
- O2 Heater Monitor Bank 1 - Sensor 2
Max: 40Count Min: 0Count
Test result value: 0Count
PASS
----

End of report.
 
#4 ·
@inthewoods

Not familiar with the data you are reporting, I looked around and found a forum on the the android app I think you are using....

Android Torque Application Test Reading Interpretation - MBWorld.org Forums

From what I gather (other forum) what you are seeing is not a big concern since you do not have an active fault code.

I would start by looking @ the short term and long term fuel trims....verify you have good spark @ each cylinder, and good fuel pressure... If all that checks out its possible you have a injector that is acting up...

Would be good to get some others to chime in... Good luck and keep us up to date on whats going on..
 
#8 ·
Factory recommendation is 1.0-1.1mm (.039-.043) I read quite a few threads on misfires and a frequent recommendation was to lower the gap. I haven't noticed any change in behavior so I plan to open them back up when I have the chance.
 
#11 ·
I've cleaned the MAF sensor, which looked pretty good anyway, and installed a new coil, but I'm still getting the same misfire behavior - a "cough" most every time I'm accelerating, either top of first gear or low in 2nd. The codes seem to clear themselves quickly but I just caught an 0302. Previously I've seen 0304.

So new plugs, wires, coil, checked O2 sensor connections, cleaned MAF.

I still get that sensor test failure from Torque Pro but don't know what to make of it reporting "sensor 4".

"02 bank 1 sensor 4, Min 64.64A Max 205.78A Current 655.2A"

I'm tempted to just replace both sensors.
 
#14 ·
It sounds like you replaced the spark plugs.... Use only NGK or Denso brands...even though the car may have come with "Champions" (they are junk)...
Any "high performance" plugs (like Bosch multi-tip) WILL cause mis-fires. KIAs only like those two and they should be gapped at .044...I use NGK platinum tips.. You might want to take a look under the hood on a dark night...Your wires might be breaking down and you may have high voltage bleeding off...

I see no mention of the mileage on your Spectra...nor any mention about having your fuel injectors cleaned.... An injector that is sticking open or closed could cause your mis-firs also... Your software looks like it's reporting the O2 levels at the time of the mis-fires for each "event"....
Dave
 
#16 ·
Mileage is ~108K miles. Wires and plugs were replaced as the first part of solving the misfire. It all seemed so simple originally. The valve cover gasket was leaking around #4 and it looked to be a simple short issue. No such luck.

I used NGK Iridium IX plugs, currently gapped at .032 since I'd seen several mentions of the lower gap to reduce misfires. I'll regap them to 1.0-1.1mm as specd, or possibly replace with cheapos if these are a known problem. I have not yet cleaned the injectors. Good point that, although it seems the misfire is moving around so I was thinking more about spark.

I'll spend more time with Torque this weekend.

Thanks for the suggestions.
 
#17 ·
The Iridiums should be OK as they are "standard" NGK designs...
I know that on my 06 Spec KIA did not use the fine tip Iridiums...just standard NGK Platinums..

I am hoping you have replaced the timing belt on your Spec....You are living dangerously if you haven't... I just replaced an engine in a 08 Hyundai Accent because the timing belt broke for the last owner...

They (timing belts) should be replaced EVERY 5ys OR 60k miles... They usually break right around 85k miles and trash the engine... The engines are good ones BUT do require TBs.and tranny drain and refill every 30k miles (for automatics)...
Dave
 
#19 ·
Do the symptoms get any worse when you fill up with gas?

Quadruple checked the firing order? Were the old plugs oil fouled? PCV?

I replaced a functional MAF in my 03 Tiburon GT with a brand new one that wreaked all kinds of havoc and cause multiple codes to come up. I reconnected the old one and everything returned to normal. The new one was a dud.

I would unplug the MAF with the engine running just to "see" if the misfire gets any worse or remains.
 
#20 ·
Haven't noticed any difference with full or empty tank.

Firing order is good. Power is great, except for the misfires.

The old plugs actually looked good, on the inside. When I first pulled them to check I found the valve cover seal around plug 4 had failed and the plug's outside half and everything under the boot was covered in gooey sludge, which seemed like the obvious cause of the misfires. No such luck.

I will try your MAF suggestion. That, re-gapping the plugs, and getting more familiar with Torque and this car's codes are my goals for this weekend.
 
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